Expanding ground anchor design



Aug. 11, 1964 G. A. JACOBSON EXPANDING GROUND ANCHOR DESIGN Filed April 15. 1960 4 Sheets-Shegt 1 1964 G. A- JACOBSON 3,144,106

EXPANDING GROUND ANCHOR DESIGN Filed April 15, 1960 v 4 Sheets-Sheet 2 INVENTOR. Gene (/9. c/a casan fittarney Aug. 11, 1964 a. A. JACOBSON 3,144,106

EXPANDING GROUND ANCHOR DESIGN Filed April 15. 1960 4 Sheets-Sheet s- IN VEN TOR. 6e t/cayiz B Aug. 11; 1964 G. A. JACOBSON EXPANDING GROUND ANCHOR DESIGN 4 Sheets-Sheet 4 Filed April 15, 1960 United States Patent Edison Company, Milwaukee, Wis., a corporation of Delaware Filed Apr. 15, 1960, Ser. No. 22,509 4 Claims. (Cl. 189-92) This invention relates to expanding ground anchors.

for securing guy wires or cables attached to the poles of an electrical power system.

An expanding ground anchor is usually inserted in a relatively small diameter cylindrical hole of sufiicient size to receive the anchor in the folded state, and the anchor blades, or flukes, are then forced outwardly into undisturbed earth surrounding the hole. Conventionally such a ground anchor includes an anchor body having flukes folded into a truncated conical configuration and resting upon a spreader member. An elongated anchor rod is usually aflixed to the spreader member and extends freely through a central aperture in the anchor body and is secured to the guy wire. Tamping on the anchor body forces the fiukes outwardly along the spreader member and into undisturbed earth.

In general, prior art ground anchors have been designed on the premise that the holding power of an anchor is primarily dependent upon the area of the flukes in expanded position. As a consequence certain prior art ground anchors have been designed with given flukes extending radially a greater distance than other flukes, while other prior art constructions have utilized flukes of rectangular cross section. These features of construction often caused the flukes to deform and the anchor to collapse under relatively light loading.

It is an object of the invention to provide a ground anchor which avoids these defects and exhibits greater holding power than prior art constructions.

I have discovered that the holding power of an expanded ground anchor is determined by both the projected area of the flukes in the undisturbed earth beyond the spreader member and the ability of the flukes to maintain their original configuration under load. I have further discovered that the portion of the expanded fluke beyond the point where the force is transmitted from spreader plate to fluke is subjected to a bending moment about this point in a manner analogous to a uniformly loaded cantilever beam. The moment arm for such bending moment is the distance from the center of gyration of the fluke area beyond the spreader plate to the point Where the force is transmitted from spreader plate to fluke. When the bending moment exceeds the flexural strength of the fluke, the anchor collapses. Prior art ground anchors which obtained large expanded area by flukes elongated in a radial direction thus had low holding strength because the relatively long moment arm of such flukes resulted in stresses beyond the elastic limit of the flukes and consequent collapse of the flukes at relatively low guy loads.

It is another object of the invention to provide a ground anchor having a maximum of fluke area beyond the spreader plate and-wherein the flukes are subjected to minimum bending moment for an anchor of such area.

Since the individual flukes of a ground anchor are subjected to a bending moment, the flexural strength of the flukes determines the ability of the flukes to maintain their original configuration. I have discovered that a fluke having a high section modulus Will retain its original configuration under a larger bending moment than that which will collapse a fluke having a lesser section modulus. Certainprior art ground anchors had flukes of rectangular cross section and consequent low section modulus and low fiexural strength which caused them to collapse under relatively low guy loads.

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It is a further object of the invention to provide a ground anchor having a maximum of fluke area beyond the spreader plate, having fiukes of high section modulus and consequent increased flexural strength, and wherein the fiukes are subjected to a minimum bending moment for said fluke area so that the anchor exhibits greater ability to maintain its original configuration and greater holding power than prior art constructions.

The forces transmitted from spreader plate to fiukes of certain prior art ground anchors were unduly concentrated at the force transfer point with the result that the flukes deformed to the extent that the section modulus, and con sequently the flexural strength, was materially diminished under relatively loW guy loads, thereby causing the anchor to collapse upon slight further increase in loading.

Another object of the invention is to provide a ground anchor wherein the forces transmitted from spreader plate to flukes are not concentrated and wherein the fiukes maintain their cross sectional configuration and section modulus even under heavy guy loading.

A standard ground anchor hole has been accepted throughout the electrical power industry. Many prior art ground anchors in the unexpanded position had flukes overlapped on one radial edge only or overlapped a minimal distance with the result that they had less than maximum area beyond the spreader plate when expanded and less than maximum holding power for an anchorcapable of insertion in the standard ground anchor hole.

It is still another object of the invention to provide a ground anchor having a maximum expanded area for a given anchor diameter in folded configuration. Another object is to provide a ground anchor which can be inserted in the standard ground anchor hole and which will have greater fluke area beyond the spreader plate, when expanded, than prior art constructions.

Prior art ground anchors had a still further deficiency in that, under sufiicient pull to deform the flukes, the fiukes moved past each other in an axial direction and thereby diminished the total effective expanded area of the anchor. As the total expanded fluke area diminished, the unit area loading increased, thereby causing greater fluke deformation to occur and subsequently causing the anchor to collapse.

It is another object of the invention to provide a fluke configuration that will become self-reinforcing under a load of sufiicient magnitude tocause deformation of the flukes. I

Conventional prior art ground anchors are of conical configuration when expanded. I have discovered that this is undesirable since a conical configuration of anchor assembly must move a relatively large distance in order to obtain sufiicient reactant force in the earth above the flukes to resist further movement of the anchor. This undesirable movement is termed creep.

It is a further object of the invention to provide a ground anchor which exhibits less creep than prior art ground anchors.

The ground anchor of the present invention comprises an anchor body having flukes folded into a conical con- The I figuration and resting upon a spreader member. anchor body has a plurality of equal size, similarly shaped flukes overlapping each other to a considerable extent on both radial edges in the unexpanded position so that a maximum projected fluke area beyond the spreader plate is provided for a given folded diameter which will fit in the standard. ground anchor hole. Each fluke is defined by radially extending slits which bisect the: sides of an equilateral polygonal blank from which the flukes are integrally formed so that maximum projected area of each fluke beyond the spreader member is provided together with a minimum moment arm for such area. Each fluke is further characterized by radial reinforcing means examass tending a substantial distance transverse to the plane of the fluke to provide a high sectional modulus which will assure that under normal rated loading the original configuration of the fluke will be maintained. Multiple point engagement is provided between each fluke in the expanded position and the spreader plate to assure that undue concentration of loading stresses cannot occur which might deform the fluke and lower its section modulus and fiexural strength. Alternate flukes are characterized by having at least one radial side thereof extending transversely to the plane of the fluke so that under a deforming guy load adjacent flukes reinforce one another, thusly preventing continued deformation of the flukes.

Tamping on the anchor body forces the flukes downwardly and outwardly along the spreader member into undisturbed earth. The flukes in expanded position rest upon the spreader member and extend beyond the periphery thereof and present an approximately planar surface to the undisturbed earth above the ground anchor, whereby creep of the anchor is minimized.

Other objects and advantages of the invention will be more readily apparent from the following detailed description taken in connection with the accompanying drawing in which:

FIG. 1 is a perspective view of a preferred embodiment of the invention in folded position;

FIG. 2 is a perspective view of the ground anchor of FIG. 1 in expanded position;

FIG. 3 is a top plan view of the ground anchor of FIG. 1 in expanded position;

FIG. 4 is a plan view of a portion of the ground anchor of FIG. 1 in unexpanded position;

FIG. 5 is a plan view of the blank from which the anchor body of the embodiment of FIG. 1 is formed;

FIG. 6 is a cross sectional view of one of the radially outer flukes of the anchor of FIG. 1 taken on line 66 of FIG. 3.

FIG. 7 is a cross sectional view of one of the radially inner flukes of the anchor of FIG. 1 taken on line 77 of FIG. 3.

FIG. 8 is a vertical section view of the ground anchor of FIG. 1 showing an inner and outer fluke in the folded position; and

FIG. 9 is a vertical section view of the ground anchor showing the flukes in expanded position as illustrated in FIG. 2.

Referring now to FIG. 1, a preferred embodiment of the ground anchor assembly of the invention includes an anchor body 10 having flukes 11, 11 shown in folded, or unexpanded, position and resting upon a spreader member 12 which may be of truncated conical configuration. The preferred embodiment preferably has six flukes of similar shape, and three alternate flukes 11 are radially inward from and overlapped by flukes 11' disposed between the alternate flukes 11. The flukes 11, 11 at their upper extremities are integral with and extend from a central, generally horizontal, pounding portion 14 of the anchor body 10. The pounding portion 14 has a central aperture 15 therethrough. The spreader member 12 also has central aperture 19 therethrough (see FIG. 8). An anchor rod 20 having a guy wire receiving eye 21 at one end and being threaded at the other end 23 extends freely through aperture 15 in anchor body 10 and through aperture 19 and is aflixed to spreader member 12 by means of a retaining nut 24 (FIG. 8) threaded on end 23. The retaining nut 24 is positioned in a nut retaining strap 25 which may be welded or otherwise permanently affixed to the underside of the spreader member 12 to provide additional metal support at the central portion of the spreader member 12.

As shown in FIG. 5, the anchor body 10 is constructed from an equilateral polygonal sheet metal blank 27 which is preferably hexagonal. The flukes 11, 11' may be formed by slitting hexagonal blank 27 radially along lines bisecting the midpoints of the sides 28 of the blank 27 so that the apices 30 of the hexagonal blank 27 form the leading edges 31, 31' of the flukes 11 and 11' respectively. The central portion 13 of the blank 27 is punched to provide both the central aperture 15 and a plurality of smaller apertures 33 radially outward from aperture 15 which preferably are the apices of an equilateral polygonal area defining the pounding portion 14. The polygonal pounding area having apertures 33 at the apices thereof preferably has the same number of sides as blank 27, but the apertures 33 are disoriented 30 from the apices 30 of the blank 27. Radially extending slits 29 define the individual flukes 11 and 11, and each slit 29 extends from one of the apertures 33 to the midpoint of one side 28 of the hexagonal blank 27.

In the folded position of anchor body 10, the radially inner alternate flukes 11 are overlapped to a considerable extent by the radially outer flukes 11. As shown in FIGS. 1 and 4 each outer fluke 11 overlaps the adjacent inner flukes 11 on both edges almost up to the reinforcing rib walls 36. The apertures 33 facilitate the bending of the flukes to the folded position and generally define the line of bending. The overlapping is accomplished by bending each alternate fluke 11 downwardly along a line 37 which is radially inward of a line connecting adjacent apertures 33 and by subsequently bending each fluke 11 downwardly along a line 38 which is radially outward of a line connecting adjacent apertures 33. While the preferred embodiment has six flukes, the equilateral polygonal blank 27 may have any desired number of sides and the ground anchor of the invention may have any desired number of flukes.

The individual flukes 11, 11 are provided with integral, radially elongated deeply embossed rib walls 36 (see FIG. 2) which extend transversely to the plane of the fiuke and to the neutral axis of a tangential cross section through the fluke. The de th of the reinforcing rib means defined by walls 36 increases in an axial direction from the pounding portion 14 to the leading edge 31, 31' of the flukes. The rib walls 36 extend a considerable distance from the neutral axis of the cross section through the fluke in order to provide a high section modulus and thus impart high flexural strength to the fluke. The preferred cross sectional configuration of the individual flukes may be described as of approximately M-shape. An upwardly curved portion 32 (see FIGS. 8 and 9) having a small radius of bend is provided adjacent the leading peripheral edge 31 of the flukes 11 in order to achieve a blunt bearing surface between the leading edge 31 and the spreader member 12 so that the leading edges 31 do not dig into the spreader member 12 during expansion of the fluke 11 along the spreader member 12.

Radial edges 41 of the radially inward flukes 11 may be bent downwardly at an angle to the plane of the fluke (see FIG. 7). The radial edges 42 of outer flukes 11' are disposed approximately in the plane of the fluke and transverse to the turned-down radial edges 41 of adjacent flukes 11. Although flukes 11, 11' are disclosed as having different radial edge configurations, the cross sectional configuration of flukes 11 and 11' is such that when they are expanded each cross section through a fluke 11 or 11 has at least three circumferentially spaced apart points positioned along a frustroconical curve complementary to the top surface of spreader member 12. These three points are shown at 42, 43, 42 in the FIG. 6 cross section through fluke 11 and at 41, 44, 41 in the FIG. 7 cross section through fluke 11. The three points define the lowermost surface of the fluke and thus enable the expanded fluke to bear upon the spreader plate 12 in at least three points (see FIGS. 6 and 7). Consequently the guy loading is transmitted from the spreader member 12 to each tangential cross section through fluke 11 in at least three distinct points.

The flukes 11' may have a small aperture 48 therethrough in proximity to the radially outer margin of the fluke. The spreader member 12 also has a plurality of spaced apart small apertures 49 therein located in such a manner that when the flukes 11, 11 are in the unexpanded position, suitable holding means such as wire 50 may be inserted through apertures 48 and 49 in the fluke and spreader member respectively to hold the anchor body to spreader member 12 as a unitary assembly.

I have discovered that the holding power of an eX- panded ground anchor is dependent upon the fluke area beyond the periphery of the spreader member and the ability of the flukes to maintain their configuration. The appreciable overlapping of flukes 11 and 11 on both edges in folded position as shown in FIGS. 1 and 4 provides a maximum expanded fluke area beyond the spreader member for a given diameter of folded anchor. A standard ground anchor hole has been accepted throughout the industry. Therefore, the appreciable overlapping achieved in my invention, with consequent maximum expanded fluke area beyond the spreader member for a given folded diameter which will fit within the standard hole, results in a ground anchor having greater holding power than that achieved by prior art anchors which can be inserted within the standard hole.

I have also discovered that the portion of each fluke beyond the periphery of the spreader member is loaded in much the same manner as a uniformly loaded cantilever beam and is subject to a bending moment about the point where the guy load is transmitted from the spreader meme ber to the fluke. The moment arm tending to bend each fluke is the distance from the center of of gyration of the fluke area beyond the spreader member to the point on the fluke where the guy load is transmitted from spreader member to fluke. Comparing two flukes of equal area beyond the spreader plate but of unequal length, the longer fluke will deform under increased guy loads before the shorter fluke because its greater lever arm results in a greater bending moment for a given guy load and consequently greater unit stress.

I have found that a fluke having a maximum of area beyond the spreader plate with a minimum bending moment arm will be achieved if the outer Periphery of each individual fluke is defined by a segment of a circle. More specifically, l have found that a ground anchor wherein the expanded flukes define a circular area will theoretically have a maximum of area beyond the spread plate with a minimum moment arm. As a practical matter a hexagonal blank 27 provides an area closely approaching the theoretical maximum accomplished by the circular expanded flukes and also provides a moment arm which closely approaches the theoretical minimum and has the additional advantage of providing a leading cutting edge. Scrap losses are also reduced by a hexagonal configuration as compared to a circular one, since the original sheets of material are rectangular and adjacent hexagonal blanks can be offset, thereby eliminating scrap which results from the material between circular blanks.

In use the ground anchor 10 in the unexpanded position shown in FIG. 1 is placed in a hole (not shown) having a diameter somewhat larger than that of the spreader member 12. The anchor within the hole may be maintained in folded position by holding means 50 which connect the anchor body 10 and spreader member 12. When the spreader member 12 is positioned at the bottom of the hole with the flukes 11, 11 resting thereon, a driving tool (not shOWn) is seated on the pounding area 14 and reciprocated axially of the hole. The initial blow severs the holding means 50 and forces the flukes ll, 11' down wardly, thereby causing the leading edges 31 of the flukes 11 to impinge upon the spreader member 12. As the flukes contact the spreader member and repeated blows strike the pounding area, the leading edges of the flukes travel downwardly and radially outwardly along the spreader member. The upwardly curved portions 32 adjacent the peripheral margin of flukes 11 permit the flukes 11 to slide freely along the surface of the spreader member 12 without exhibiting a tendency to dig into the d spreader member as frequently occurred in prior art devices. In addition to providing a better bearing between fluke and spreader member, the upwardly curved portion i 32 minimizes damage to the protective coating on the spreader member, and consequently the spreader member is less susceptible to corrosive soil conditions and/ or electrolysis.

When the leading edges of the flukes reach the outer periphery of the spreader member, they are forced into undisturbed earth. Entry of the flukes into undisturbed earth is facilitated by the cutting and scooping action of the leading fluke edges 31, 31' and the recessed portion of the flukes between rib walls 36. When the underside of the pounding portion 14 of the anchor body 10 contacts the upper face of the spreader member 12, a metal-to-metal sound will be heard, thereby informing the operator that the ground anchor is fully expanded.

I have discovered that in an expanded ground anchor the turned-down edges 41 of flukes 11 coact with the radial edges 42 of flukes 11' to cause the earth to bridge between adjacent flukes so that the flukes, in eifect, mutually interfere and prevent movement of one fluke in an axial direction past the other flukes. This mutual interference occurs just as if the flukes were physically bearing against one another, and the interference effect is a result of the particular fluke configuration. This mutual interference prevents substantial deformation of any one fluke and thus maintains maximum anchor holding power in that it prevents increased loading on the remaining flukes when one fluke was deformed to the extent that it lost holding power as occurred in prior art constructions.

The flukes 11 and 11' are generally of uniform length and size which results in substantially equal loads being applied on all flukes. The similarity of flukes is also advantageous when the flukes are expanding since they penetrate into the undisturbed earth to the same degree and thus are more likely to fully expand even if stones interfere with outward movement of the flukes.

The reinforcing rib walls 36 assure that the fluke will retain its original configuration under a larger bending moment than will a fluke without rib walls. The rib walls increase the section modulus of a tangential cross section through the fluke since with such configuration a substantial portion of material is spaced a considerable distance from the neutral axis of the cross section through the fluke, thereby increasing the section modulus and the flexural strength of the fluke. However, a fluke, in addition to being subject to a bending moment, is also subject to stress at the point of load transfer from spreader member to fluke. If the fluke has only a single point of bearing against the spreader member as in prior art construction, the entire guy load is in elfect applied in one radial cross section through the fluke and may thus result in sufficiently high unit stress at the bearing point to deform the fluke. The flukes 11 and 11' having a cross section of M-shaped configuration are provided with both a high section modulus and a multiplicity of bearing points against the spreader member. Consequently such construction provides a lower unit fiber stress and increases the flexural strength of the individual flukes and the holding strength of the ground anchor.

The ground anchor of the invention when positioned in the earth with the flukes expanded presents an approxi-,

mately planar surface to the undisturbed earth thereabove as a result of the radially increasing depth of the rib walls 36. Some compression of the soil above a ground anchor must take place before the anchor achieves its maximum holding power. The movement of the anchor in compressing the soil above it is termed creep. Since the anchor of the invention presents an approximately planar surface to the soil above it, creep of the anchor will be at a minimum in comparison to prior art anchors which were of truncated conical configuration when ex panded.

While only a particular embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications can be made therefrom without departing from the invention, and therefore it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. An expansible anchor assembly comprising, in combination, a spreader member, an anchor rod secured to said spreader member, an anchor body integrally formed of an equilateral polygonal blank having a central opening through which said anchor rod extends and a central polygonal pounding area surrounding said opening and provided with the same number of sides as said blank, said anchor body having a plurality of slits therein extending outward from the apices of said polygonal pounding area to the sides of said blank and defining a plurality of flukes equal in number to said sides, each of said flukes having turned substantially radial edges and at least one downwardly recessed, radially extending reinforcing rib portion extending transversely a substantial distance from the neutral axis of the cross section of said fluke for increasing the section modulus of said cross section and increasing the flexural strength of said fluke, said flukes being bent downward into a folded generally frustoconical configuration, said anchor body resting on said spreader member so that tamping on said pounding portion will expand said flukes outward along said spreader member and into undisturbed earth with each fluke having at least three surfaces, including surfaces presented by said turned substantially radial edge portions, bearing against said spreader member, alternate flukes in folded position overlaying flukes adjacent thereto a substantial distance on both edges, whereby said anchor body will have maximum expanded area and maximum holding power for a predetermined diameter of said generally conical configuration.

2. An expansible ground anchor assembly comprising, in combination, an anchor rod, an equilateral polygonal anchor body member having a central aperture therethrough for receiving said anchor rod and having a poly onal central portion surrounding said aperture which serves as a pounding area, said anchor body member having a plurality of slits therein extending radially outward from the apices of said polygonal pounding area and defining a plurality of flukes equal in number to the sides of said polygonal anchor body member, said flukes being bent downward into a'folded truncated conical configuration and alternatetflukes overlapping adjacent flukes on both edges, a spreader member secured to said anchor rod, said anchor body resting on said spreader member so that tamping on said pounding area expands said flukes outward along said spreader member, said flukes having turned substantially radial edge portions and a centrally disposed, downwardly recessed radially extending reinforcing rib for increasing the flexural strength thereof against bending in an axial direction and the underside of each fluke facing said spreader member having at least three circumferentially spaced apart surfaces including surfaces presented by said turned substantially radial edge portions adapted to simultaneously engage said spreader member when said flukes are expanded.

3. An expansible ground anchor assembly comprising, in combination, a spreader plate, an anchor rod affixed to said spreader plate, an anchor body integrally formed of an equilateral polygonal sheet metal blank having a central aperture therethrough for receiving said anchor rod and having an equilateral polygonal central portion surrounding said aperture and serving as a pounding area, said anchor body having a plurality of slits therein extending radially outward from the apices of said polygonal pounding area to the midportion of the sides of said blank defining a plurality of equal sized flukes, each of said flukes having turned substantially radial edge portions and a generally radial downwardly recessed reinforcing rib the depth of which increases radially outwardly extending transversely a substantial distance from the neutral axis of the cross section of said fiuke for increasing the section modulus of said cross section and increasing the fiexural strength of said fluke, said flukes being bent downward into a folded, generally frusto-conical configuration and alternate flukes overlapping flukes adjacent thereto a substantial distance on both edges, said substantially radial edge portions of adjacent flukes being contiguous with a portion of each edge portion bearing against said spreader plate in the expanded position and certain of said flukes having at least one substantially radial side extending transversely to the plane thereof, whereby under suflicient load to deform said flukes the substantially radial edges of adjacent flukes interfere so that said flukes reinforce each other and resist further deformation. 7

4. An expansible ground anchor assembly comprising, in combination, an anchor rod, an equilateral polygonal anchor body member having an even number of sides and a central aperture therethrough for receiving said anchor rod and having a polygonal central portion surrounding said aperture which serves as a pounding area, said anchor member having a plurality of radially extending slits which extend generally radially from the apices of said polygonal pounding area, thereby defining a plurality of flukes equal in number to the sides of said polygonal anchor body member with each fluke having turned substantially radial edge portions and a radially outwardly deepening, downwardly recessed rib, said flukes being bent downward into a folded truncated conical configuration and alternate flukes overlapping adjacent flukes on both edges, the substantially radial edges of adjacent flukes being contiguous in the expanded position with alternate flukes having substantially radial sides extending transversely to the plane of the fluke, said anchor body resting on said spreader member so that tamping on said pounding area expands said flukes outward along said spreader plate and into undisturbed earth with each fluke having at least three surfaces including surfaces presented by said turned substantially radial portions bearing against said spreader member, the outer margin of certain of said flukes being turned up on a slight radius, whereby said turned-up edges of said flukes are adapted to slide along the upper surface of said spreader plate and exhibit no tendency to dig into said surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,320,464 Pieper June 1, 1943 2,570,646 Cole Oct. 9, 1951 2,723,733 Petersen Nov. 15-, 1955' 2,905,288 Runde Sept. 22, 1959 

1. AN EXPANSIBLE ANCHOR ASSEMBLY COMPRISING, IN COMBINATION, A SPREADER MEMBER, AN ANCHOR ROD SECURED TO SAID SPREADER MEMBER, AN ANCHOR BODY INTEGRALLY FORMED OF AN EQUILATERAL POLYGONAL BLANK HAVING A CENTRAL OPENING THROUGH WHICH SAID ANCHOR ROD EXTENDS AND A CENTRAL POLYGONAL POUNDING AREA SURROUNDING SAID OPENING AND PROVIDED WITH THE SAME NUMBER OF SIDES AS SAID BLANK, SAID ANCHOR BODY HAVING A PLURALITY OF SLITS THEREIN EXTENDING OUTWARD FROM THE APICES OF SAID POLYGONAL POUNDING AREA TO THE SIDES OF SAID BLANK AND DEFINING A PLURALITY OF FLUKES EQUAL IN NUMBER TO SAID SIDES, EACH OF SAID FLUKES HAVING TURNED SUBSTANTIALLY RADIAL EDGES AND AT LEAST ONE DOWNWARDLY RECESSED, RADIALLY EXTENDING REINFORCING RIB PORTION EXTENDING TRANSVERSELY A SUBSTANTIAL DISTANCE FROM THE NEUTRAL AXIS OF THE CROSS SECTION OF SAID FLUKE FOR INCREASING THE SECTION MODULUS OF SAID CROSS SECTION AND INCREASING THE FLEXURAL STRENGTH OF SAID FLUKE, SAID FLUKES BEING BENT DOWNWARD INTO A FOLDED GENERALLY FRUSTOCONICAL CONFIGURATION, SAID ANCHOR BODY RESTING ON SAID SPREADER MEMBER SO THAT TAMPING ON SAID POUNDING PORTION WILL EXPAND SAID FLUKES OUTWARD ALONG SAID SPREADER MEMBER AND INTO UNDISTURBED EARTH WITH EACH FLUKE HAVING AT LEAST THREE SURFACES, INCLUDING SURFACES PRESENTED BY SAID TURNED SUBSTANTIALLY RADIAL EDGE PORTIONS, BEARING AGAINST SAID SPREADER MEMBER, ALTERNATE FLUKES IN FOLDED POSITION OVERLYING FLUKES ADJACENT THERETO A SUBSTANTIAL DISTANCE ON BOTH EDGES, WHEREBY SAID ANCHOR BODY WILL HAVE MAXIMUM EXPANDED AREA AND MAXIMUM HOLDING POWER FOR A PREDETERMINED DIAMETER OF SAID GENERALLY CONICAL CONFIGURATION. 